1. Technical Field of the Invention
The present invention relates to a main unit address restricted notification system for notifying an address of a system main unit such as a system control unit when connection of client terminals is started.
2. Description of the Related Art
Priorly, in a network system including network terminals such as local area network (LAN) telephones and network computers (NCs), in a case where, from network terminals to a server for administrating addresses (hereinafter, referred to as a DHCP server), a request for an address of a server for accommodating these network terminals (hereinafter, referred to as an NC server) is made by means of a dynamic host configuration protocol (hereinafter, referred to as a DHCP), if the NC server address has been registered in the DHCP server, the DHCP server unconditionally notifies any network terminals of the NC server address.
As a network system similar to such a LAN telephone system, the following technique has been disclosed in Japanese Unexamined Patent Publication No. 2000-92107.
In the concrete network system, first and second LANs are connected to a network, and furthermore, a directory server is connected thereto. In response to a request for IP address acquisition from an NC connected to the first LAN, a DHCP server, which is similarly connected to the first LAN, assigns an IP address to the NC and also replies with an IP address of the directory server. The NC broadcasts a request for IP address acquisition at start-up, accesses the directory server by using the IP address answered from the DHCP server, and acquires the IP address of the NC server. Then, the NC accesses an NC server on the second LAN by using the IP address acquired and boots a basic program.
As such, the DHCP server notifies the NCs, from which an address request has been made, of the NC server address via the server which has recognized the NC server address and is called a directory server, although it is indirectly performed.
However, in such a prior network system, the NC server address is notified to all of the NCs from which a request has been made, therefore, even an illegally diverted NC can connect to the NC server.
Namely, a problem exists such that authorization is not carried out at the DHCP server and the NC server address is notified to all of the NCs which have made a request for the NC server address.